Iron-based molecular sieve catalyst, preparation method and application thereof

Abstract

The present invention relates to the technical field of catalysts, and discloses an iron-based molecular sieve catalyst, a preparation method and applications thereof, the iron-based molecular sieve catalyst comprises the following raw materials by mass: a molecular sieve, a solvent and an iron ion exchanger, and the loading amount of the iron element in the catalyst is 0.5-6%; the catalyst can catalyze a reaction for preparing ethylene and propylene through dehydrogenation of ethane and propane, has relatively high ethylene and propylene selectivity, remarkably improves the conversion efficiency of ethylene and propylene, can be regenerated in air, and is low in regeneration cost, safe and environment-friendly compared with a platinum-based molecular sieve catalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to an iron-based molecular sieve catalyst, a preparation method and applications thereof. Background Art

[0002] Light olefins, such as ethylene and propylene, are among the most important platform chemicals in the modern chemical industry and are typically produced by naphtha steam cracking. In recent years, the development of non-petroleum-based routes to ethylene and propylene has attracted considerable attention, with successful applications in methanol-to-olefins, syngas-to-olefins, and bioethanol dehydration processes. Over the past decade, the supply of ethane has surged more than 15-fold due to increased shale gas production. While steam cracking of ethane has been used industrially to produce ethylene, it is a highly endothermic process requiring high reaction temperatures and producing byproducts such as carbon dioxide and methane. In contrast, direct catalytic dehydrogenation of ethane and propane is a promising technology for producing ethylene and propylene. However, in the oxidative dehydrogenation of ethane and propane, oxygen in the feed leads to overoxidation, producing unwanted byproducts such as carbon monoxide and carbon dioxide, resulting in reduced selectivity for ethylene or propylene.

[0003] Currently, platinum-based catalysts are mainly used in the prior art to catalyze the dehydrogenation of alkanes to olefins. For example, Publication No. CN105251486B discloses a supported platinum-based catalyst for the dehydrogenation of propane to propylene and its preparation method. Publication No. CN111135856A discloses the preparation and application of a platinum-based skeleton iron molecular sieve alkane dehydrogenation catalyst. Publication No. CN118988302A discloses a Zn-regulated PtSn / Al2O3 catalyst, its preparation method, and its application in propane dehydrogenation. Although platinum-based molecular sieve catalysts currently have high selectivity, platinum is a precious metal and has a high cost of use. In addition, deactivated platinum molecular sieve catalysts need to be oxidized and regenerated using hydrogen chloride, which is costly and complex. Summary of the Invention

[0004] In response to the problem of high raw material cost of platinum-based molecular sieve catalysts in the prior art, the present invention provides an iron-based molecular sieve catalyst, a preparation method and its application. The iron-based molecular sieve catalyst has high ethylene and propylene selectivity in the reaction of dehydrogenation of ethane and propane to produce ethylene and propylene, with the selectivity reaching %. In addition, the deactivated iron-based molecular sieve catalyst can be regenerated in air, with low regeneration cost and simple process.

[0005] The specific technical solutions of the present invention are: An iron-based molecular sieve catalyst is characterized in that the raw materials include, by mass percentage, molecular sieve, solvent, and iron ion exchanger, and the loading amount of iron element in the catalyst is 0.5-6%.

[0006] Preferably, the molecular sieve is a zeolite molecular sieve, and the silicon-aluminum ratio of the zeolite molecular sieve is 5 to 10,000:1.

[0007] Preferably, the molecular sieve is one or more of ZSM-5, CHA, FER, Beta and MOR.

[0008] Preferably, the iron ion exchanger is one or more of ferric chloride, ferric nitrate, ferric sulfate, ferrous sulfate and ferric carbonate.

[0009] Preferably, the solvent is one or more of methanol, ethanol, ethylene glycol, water or glycerol.

[0010] The present invention provides an iron-based molecular sieve catalyst. This catalyst uses an iron salt as an iron ion exchange agent to undergo an ion exchange reaction with a zeolite molecular sieve, loading iron ions into the pores of the zeolite molecular sieve. This catalyst can catalyze the dehydrogenation of ethane and propane to ethylene and propylene, exhibiting high ethylene and propylene selectivity and significantly improving the conversion efficiency of ethylene and propylene. Furthermore, this catalyst can be regenerated in air, which reduces regeneration costs compared to platinum-based molecular sieve catalysts and is safer and more environmentally friendly.

[0011] A method for preparing the above-mentioned iron-based molecular sieve catalyst for dehydrogenating light alkanes to produce light olefins comprises the following steps: preparing an ion exchange solution with an iron ion exchanger and a solvent, subjecting the ion exchange solution and a zeolite molecular sieve to ion exchange treatment to prepare a precursor, washing the precursor with a solvent and drying it, and calcining it after drying to prepare the iron-based molecular sieve catalyst for dehydrogenating light alkanes to produce light olefins.

[0012] Preferably, the conditions for the ion exchange treatment include: a temperature of 60 to 95° C., a time of 20 to 120 min, and a concentration of the ion exchange solution of 0.01 to 0.2 mol / L.

[0013] Preferably, the calcination conditions include: temperature of 600-1000° C., and heat preservation for 2-4 hours.

[0014] Preferably, the drying treatment conditions include: temperature 60-100° C., time 0.5-24 h.

[0015] An application of the above-mentioned iron-based molecular sieve catalyst in the dehydrogenation of light alkanes to light olefins includes the following steps: dehydrogenating light alkanes and catalysts to produce light olefins, wherein the light alkanes include methane and ethane, and the light olefins are ethylene and propylene.

[0016] Preferably, the dehydrogenation reaction conditions include: inert gas atmosphere, temperature 550-700°C, mass space velocity 0.2-5h -1 .

[0017] Preferably, the mass percentage of the auxiliary agent is 0.1 to 0.5%.

[0018] Preferably, the inert atmosphere is nitrogen.

[0019] Compared with the existing technology, this application has the following technical effects: The present invention provides an iron-based molecular sieve catalyst, which can catalyze the dehydrogenation of ethane and propane to produce ethylene and propylene, has high selectivity for ethylene and propylene, and significantly improves the conversion efficiency of ethylene and propylene; The catalyst can be regenerated in air. Compared with platinum-based molecular sieve catalysts, it has lower regeneration costs and is safer and more environmentally friendly. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the embodiments.

[0021] Example 1: A method for preparing an iron-based molecular sieve catalyst comprises the following steps: heating a 0.2 mol / L methanol solution of iron carbonate in an 80°C water bath to prepare an ion exchange solution, placing H-type CHA (silicon-aluminum ratio of 15:1) in the ion exchange solution for 120 minutes to prepare a precursor, washing the precursor three times with methanol, drying the precursor at 80°C for 2 hours, calcining the dried precursor at 1000°C, keeping the temperature for 4 hours, and then cooling to room temperature to prepare an iron-based molecular sieve catalyst Fe-HCHA, wherein the iron loading in the iron-based molecular sieve catalyst Fe-HCHA is 1.6 wt%; The application of the above-mentioned iron-based molecular sieve catalyst in the dehydrogenation of light alkanes to light olefins comprises the following steps: placing the iron-based molecular sieve catalyst Fe-HCHA as a catalyst in the reaction of ethane dehydrogenation to ethylene, the reaction conditions being a temperature of 650°C, a nitrogen atmosphere, a volume ratio of ethane to nitrogen of 0.6:0.4, and an ethane mass space velocity of 5h -1 ; A method for regenerating the above-mentioned deactivated iron-based molecular sieve catalyst comprises the following steps: placing the deactivated iron-based molecular sieve catalyst at a temperature of 650° C. and introducing air for calcination for 30 minutes to complete the regeneration.

[0022] Example 2: A method for preparing an iron-based molecular sieve catalyst comprises the following steps: heating a 0.2 mol / L methanol solution of iron carbonate in an 80°C water bath to prepare an ion exchange solution, placing H-type CHA (silicon-aluminum ratio of 15:1) in the ion exchange solution for 120 minutes to prepare a precursor, washing the precursor three times with methanol, drying the precursor at 80°C for 2 hours, calcining the dried precursor at 1000°C, keeping the temperature for 4 hours, and then cooling to room temperature to prepare an iron-based molecular sieve catalyst Fe-HCHA, wherein the iron loading in the Fe-HCHA is 1.7 wt%; The application of the above-mentioned iron-based molecular sieve catalyst in the dehydrogenation of light alkanes to light olefins comprises the following steps: placing the iron-based molecular sieve catalyst Fe-HCHA as a catalyst in the reaction of ethane dehydrogenation to ethylene, the reaction conditions being a temperature of 650°C, a nitrogen atmosphere, a volume ratio of ethane to nitrogen of 0.6:0.4, and an ethane mass space velocity of 5h -1 ; A method for regenerating the above-mentioned deactivated iron-based molecular sieve catalyst comprises the following steps: placing the deactivated iron-based molecular sieve catalyst at a temperature of 650° C. and introducing air for calcination for 30 minutes to complete the regeneration.

[0023] Example 3: A method for preparing an iron-based molecular sieve catalyst comprises the following steps: heating a 0.2 mol / L methanol solution of iron carbonate in an 80°C water bath to prepare an ion exchange solution, placing H-type CHA (silicon-aluminum ratio of 15:1) in the ion exchange solution for 120 minutes to prepare a precursor, washing the precursor three times with methanol, drying the precursor at 80°C for 2 hours, calcining the dried precursor at 1000°C, keeping the temperature for 4 hours, and then cooling to room temperature to prepare an iron-based molecular sieve catalyst Fe-HCHA, wherein the iron loading in the iron-based molecular sieve catalyst Fe-HCHA is 1.8 wt%; The application of the above-mentioned iron-based molecular sieve catalyst in the dehydrogenation of light alkanes to light olefins comprises the following steps: placing the iron-based molecular sieve catalyst Fe-HCHA as a catalyst in the reaction of ethane dehydrogenation to ethylene, the reaction conditions being a temperature of 650°C, a nitrogen atmosphere, a volume ratio of ethane to nitrogen of 0.6:0.4, and an ethane mass space velocity of 5h -1 ; A method for regenerating the above-mentioned deactivated iron-based molecular sieve catalyst comprises the following steps: placing the deactivated iron-based molecular sieve catalyst at a temperature of 650° C. and introducing air for calcination for 30 minutes to complete the regeneration.

[0024] Example 4: A method for preparing an iron-based molecular sieve catalyst comprises the following steps: heating a 0.2 mol / L methanol solution of iron carbonate in an 80°C water bath to prepare an ion exchange solution, placing H-type CHA (silicon-aluminum ratio of 15:1) in the ion exchange solution for 120 minutes to prepare a precursor, washing the precursor three times with methanol, drying the precursor at 80°C for 2 hours, calcining the dried precursor at 1000°C, maintaining the temperature for 4 hours, and then cooling to room temperature to prepare an iron-based molecular sieve catalyst Fe-HCHA, wherein the iron loading in the Fe-HCHA is 1.9 wt%; The application of the above-mentioned iron-based molecular sieve catalyst in the dehydrogenation of light alkanes to light olefins comprises the following steps: placing the iron-based molecular sieve catalyst Fe-HCHA as a catalyst in the reaction of ethane dehydrogenation to ethylene, the reaction conditions being a temperature of 650°C, a nitrogen atmosphere, a volume ratio of ethane to nitrogen of 0.6:0.4, and an ethane mass space velocity of 5h -1 ; A method for regenerating the above-mentioned deactivated iron-based molecular sieve catalyst comprises the following steps: placing the deactivated iron-based molecular sieve catalyst at a temperature of 650° C. and introducing air for calcination for 30 minutes to complete the regeneration.

[0025] Example 5: A preparation method of an iron-based molecular sieve catalyst comprises the following steps: heating a 0.1 mol / L ferric nitrate methanol solution in a 60°C water bath to prepare an ion exchange solution, placing H-type ZSM-5 (silicon-aluminum ratio of 5:1) in the ion exchange solution for 20 minutes to prepare a precursor, washing the precursor once with methanol, drying the precursor at 60°C for 0.5 hours, calcining the dried precursor at 600°C, keeping the temperature for 2 hours, and then cooling the temperature to room temperature to prepare an iron-based molecular sieve catalyst. A molecular sieve catalyst Fe-HZSM-5, wherein the iron loading in the iron-based molecular sieve catalyst Fe-HZSM-5 is 6.2 wt%; an application of the iron-based molecular sieve catalyst in the dehydrogenation of light alkanes to light olefins, comprising the following steps: placing the iron-based molecular sieve catalyst Fe-HZSM-5 as a catalyst in an ethane dehydrogenation reaction to produce ethylene, wherein the reaction conditions are a temperature of 550° C., a nitrogen atmosphere, a volume ratio of ethane to nitrogen of 0.05:0.95, and an ethane mass space velocity of 0.2 h -1 ; A method for regenerating the above-mentioned deactivated iron-based molecular sieve catalyst comprises the following steps: placing the deactivated iron-based molecular sieve catalyst at a temperature of 650° C. and introducing air for calcination for 30 minutes to complete the regeneration.

[0026] Example 6: A method for preparing an iron-based molecular sieve catalyst comprises the following steps: heating a 0.01 mol / L ferric chloride ethanol solution in an 80°C water bath to prepare an ion exchange solution, placing a Na-type FER (silicon-aluminum ratio of 10:1) in the ion exchange solution for 60 minutes to prepare a precursor, washing the precursor twice with ethanol, drying the precursor at 60°C for 0.5 hours, calcining the dried precursor at 750°C, keeping the temperature for 4 hours, and then cooling to room temperature to prepare an iron-based molecular sieve catalyst Fe-NaFER, wherein the iron loading amount of the iron-based molecular sieve catalyst Fe-NaFER is 3.1 wt%; An application of the above-mentioned iron-based molecular sieve catalyst in the dehydrogenation of light alkanes to light olefins comprises the following steps: placing the iron-based molecular sieve catalyst Fe-NaFER as a catalyst in the reaction of propane dehydrogenation to propylene, the reaction conditions being a temperature of 600°C, a nitrogen atmosphere, a volume ratio of propane to nitrogen of 0.1:0.9, and a propane mass space velocity of 1h -1 ; A method for regenerating the above-mentioned deactivated iron-based molecular sieve catalyst comprises the following steps: placing the deactivated iron-based molecular sieve catalyst at a temperature of 650° C. and introducing air for calcination for 30 minutes to complete the regeneration.

[0027] Example 7: A method for preparing an iron-based molecular sieve catalyst comprises the following steps: heating a 0.1 mol / L ferric sulfate ethylene glycol solution in a 95°C water bath to prepare an ion exchange solution, placing K-type Beta (silicon-aluminum ratio of 20:1) in the ion exchange solution for 20 minutes to prepare a precursor, washing the precursor three times with ethylene glycol, drying the precursor at 80°C for 2 hours, calcining the dried precursor at 750°C, keeping the temperature for 4 hours, and then cooling to room temperature to prepare an iron-based molecular sieve catalyst Fe-KBeta, wherein the iron loading in the iron-based molecular sieve catalyst Fe-KBeta is 1.6 wt%; An application of the above-mentioned iron-based molecular sieve catalyst in the dehydrogenation of light alkanes to light olefins comprises the following steps: placing the iron-based molecular sieve catalyst Fe-KBeta as a catalyst in the reaction of propane dehydrogenation to propylene, the reaction conditions being a temperature of 700°C, a nitrogen atmosphere, a volume ratio of propane to nitrogen of 0.4:0.6, and a propane mass space velocity of 1h -1 ; A method for regenerating the above-mentioned deactivated iron-based molecular sieve catalyst comprises the following steps: placing the deactivated iron-based molecular sieve catalyst at a temperature of 650° C. and introducing air for calcination for 30 minutes to complete the regeneration.

[0028] Example 8: A method for preparing an iron-based molecular sieve catalyst comprises the following steps: heating a 0.2 mol / L methanol solution of iron carbonate in an 80°C water bath to prepare an ion exchange solution, placing H-type MOR (silicon-aluminum ratio of 50:1) in the ion exchange solution for 20 minutes to prepare a precursor, washing the precursor three times with methanol, drying the precursor at 80°C for 2 hours, calcining the dried precursor at 1000°C, keeping the temperature for 4 hours, and then cooling to room temperature to prepare an iron-based molecular sieve catalyst Fe-HMOR, wherein the iron loading amount of the iron-based molecular sieve catalyst Fe-HMOR is 0.6 wt%; An application of the above-mentioned iron-based molecular sieve catalyst in the dehydrogenation of light alkanes to light olefins comprises the following steps: placing the iron-based molecular sieve catalyst Fe-HMOR as a catalyst in the reaction of ethane dehydrogenation to ethylene, the reaction conditions being a temperature of 650°C, a nitrogen atmosphere, a volume ratio of ethane to nitrogen of 0.6:0.4, and an ethane mass space velocity of 5h -1 ; A method for regenerating the above-mentioned deactivated iron-based molecular sieve catalyst comprises the following steps: placing the deactivated iron-based molecular sieve catalyst at a temperature of 650° C. and introducing air for calcination for 30 minutes to complete the regeneration.

[0029] Example 9: A method for preparing an iron-based molecular sieve catalyst comprises the following steps: impregnating an equal volume of 14 mg of ferric nitrate nonahydrate onto 1 g of H-type ZSM-5 (silicon-aluminum ratio of 10,000:1), calcining at 650° C., keeping the temperature for 2 hours, and then cooling the temperature to room temperature to prepare an iron-based molecular sieve catalyst Fe-HZSM-5, wherein the iron loading amount in the iron-based molecular sieve catalyst Fe-HZSM-5 is 0.2 wt%.

[0030] The application of the above-mentioned iron-based molecular sieve catalyst in the dehydrogenation of light alkanes to light olefins comprises the following steps: placing the iron-based molecular sieve catalyst Fe-HZSM-5 as a catalyst in the reaction of dehydrogenation of propane to propylene, the reaction conditions being a temperature of 650°C, a nitrogen atmosphere, a volume ratio of propane to nitrogen of 0.3:0.7, and a propane mass space velocity of 1h -1 .

[0031] A method for regenerating the above-mentioned deactivated iron-based molecular sieve catalyst comprises the following steps: placing the deactivated iron-based molecular sieve catalyst at a temperature of 650° C. and introducing air for calcination for 30 minutes to complete the regeneration.

[0032] Comparative Example 1: Comparative Example 1 uses a platinum-based molecular sieve catalyst PtSn / Al2O3 as a catalyst for ethane dehydrogenation to ethylene, comprising the following steps: placing the platinum-based molecular sieve catalyst PtSn / Al2O3 as a catalyst in the ethane dehydrogenation to ethylene reaction, the reaction conditions being a temperature of 650°C, a nitrogen atmosphere, a volume ratio of ethane to nitrogen of 0.3:0.7, and an ethane mass space velocity of 1h -1 ; The above-mentioned method for regenerating a deactivated platinum-based molecular sieve catalyst includes the following steps: decoking, oxychlorination, removal of excess chlorine and water, and catalyst reduction. After the catalyst is coked, the active platinum metal centers aggregate. Therefore, oxidative redispersion of the active metal is necessary to restore the catalyst's activity. A small amount of water is generated during the coking process, which reacts with chlorine to form HCl. Contact with chlorine and dry air oxidizes the platinum on the catalyst and effectively redisperses it.

[0033] Comparative Example 2: Comparative Example 2 uses a platinum-based molecular sieve catalyst PtSn / Al2O3 as a catalyst for propane dehydrogenation to propylene, comprising the following steps: placing the platinum-based molecular sieve catalyst PtSn / Al2O3 as a catalyst in a propane dehydrogenation to propylene reaction, the reaction conditions being a temperature of 650°C, a nitrogen atmosphere, a volume ratio of propane to nitrogen of 0.3:0.7, a propane mass space velocity of 1h -1 ; The above-mentioned method for regenerating the deactivated platinum-based molecular sieve catalyst includes the following steps: decoking, oxychlorination reaction, removal of excess chlorine and water, and catalyst reduction. After the catalyst is coked, the active center metal platinum will aggregate together. Therefore, in order to restore the activity of the catalyst, the active metal needs to be oxidized and redispersed. Because a small amount of water will be generated during the coking process, the water will react with chlorine to form HCl. Through contact with chlorine and dry air, the platinum on the catalyst is oxidized and well redispersed on the catalyst.

[0034] Comparative Example 3: Compared with Example 1, the iron loading in the catalyst in Comparative Example 3 is too small, with a loading of 0.5%, comprising the following steps: heating a 0.2 mol / L methanol solution of iron carbonate in a water bath at 80° C. to prepare an ion exchange solution, placing H-type CHA (silicon-aluminum ratio of 15:1) in the ion exchange solution for ion exchange treatment for 120 min to prepare a precursor, washing the precursor three times with methanol, drying the precursor at 80° C. for 2 h, and then calcining the dried precursor at 1000° C., keeping the temperature for 4 h, and then cooling to room temperature to prepare an iron-based molecular sieve catalyst Fe-HCHA, wherein the iron loading in the iron-based molecular sieve catalyst Fe-HCHA is 0.5 wt%; The application of the above-mentioned iron-based molecular sieve catalyst in the dehydrogenation of light alkanes to light olefins comprises the following steps: placing the iron-based molecular sieve catalyst Fe-HCHA as a catalyst in the reaction of ethane dehydrogenation to ethylene, the reaction conditions being a temperature of 650°C, a nitrogen atmosphere, a volume ratio of ethane to nitrogen of 0.6:0.4, and an ethane mass space velocity of 5h -1 ; A method for regenerating the above-mentioned deactivated iron-based molecular sieve catalyst comprises the following steps: placing the deactivated iron-based molecular sieve catalyst at a temperature of 650° C. and introducing air for calcination for 30 minutes to complete the regeneration.

[0035] Comparative Example 4: Compared with Example 1, the iron loading in the catalyst in Comparative Example 4 is too large, with a loading of 10%, comprising the following steps: heating a 0.2 mol / L methanol solution of iron carbonate in a water bath at 80° C. to prepare an ion exchange solution, placing H-type CHA (silicon-aluminum ratio of 15:1) in the ion exchange solution for ion exchange treatment for 120 min to prepare a precursor, washing the precursor three times with methanol, drying the precursor at 80° C. for 2 h, and then calcining the dried precursor at 1000° C., keeping the temperature for 4 h, and then cooling to room temperature to prepare an iron-based molecular sieve catalyst Fe-HCHA, wherein the iron loading in the iron-based molecular sieve catalyst Fe-HCHA is 10 wt%; The application of the above-mentioned iron-based molecular sieve catalyst in the dehydrogenation of light alkanes to light olefins comprises the following steps: placing the iron-based molecular sieve catalyst Fe-HCHA as a catalyst in the reaction of ethane dehydrogenation to ethylene, the reaction conditions being a temperature of 650°C, a nitrogen atmosphere, a volume ratio of ethane to nitrogen of 0.6:0.4, and an ethane mass space velocity of 5h -1 ; A method for regenerating the above-mentioned deactivated iron-based molecular sieve catalyst comprises the following steps: placing the deactivated iron-based molecular sieve catalyst at a temperature of 650° C. and introducing air for calcination for 30 minutes to complete the regeneration.

[0036] Test example: The conversion rates of ethane, ethylene, propane and propylene in Examples 1 to 7 and Comparative Examples 1 to 4 were tested, and the test results are shown in Table 1; Table 1 Test results As shown in Table 1, the initial low-carbon alkane conversion rate of the iron-based molecular sieve catalyst prepared in Examples 1 to 9 can reach up to 43.2%, and the initial low-carbon alkane selectivity can reach 94.2%. The iron-based molecular sieve catalyst provided by the present invention is compared with the PtSn / Al2O3 catalyst in the prior art. Although the initial low-carbon alkane conversion rate and the initial low-carbon alkane selectivity are reduced, the difference is not significant. This result shows that the iron-based molecular sieve catalyst provided by the present invention also has a relatively excellent catalytic performance for converting low-carbon alkanes to low-carbon olefins. In addition, the iron-based molecular sieve catalyst provided by the present invention can be regenerated by calcining in air, while the PtSn / Al2O3 catalyst requires oxychlorination reaction to complete regeneration. The iron-based molecular sieve catalyst provided by the present invention has a simple regeneration process and low regeneration cost compared with the PtSn / Al2O3 catalyst.

[0037] Examples 1 to 4 are iron-based molecular sieve catalysts made by using molecular sieve HCHA (Si:Al=15:1) to load iron ions. Experiments have found that the iron loading in the iron-based molecular sieve catalyst has an important influence on the initial alkane conversion rate and the selectivity of light olefins. When the iron loading is too low or too high, the catalytic performance of the iron-based molecular sieve catalyst is reduced.

[0038] In addition, the present invention found that the conversion rate of light alkanes of the Fe-HCHA catalyst can still reach more than 30% after 150 hours, while the conversion rate of light alkanes of other catalysts is still basically zero. The conversion rate of light alkanes of the PtSn / Al2O3 catalyst in the prior art is reduced to less than 10% after 150 hours of catalysis.

[0039] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. An iron-based molecular sieve catalyst, characterized in that: The raw materials include, by mass percentage, molecular sieve, solvent, and iron ion exchanger. The loading amount of iron element in the catalyst is 0.5-6%.

2. The iron-based molecular sieve catalyst according to claim 1, characterized in that: The molecular sieve is a zeolite molecular sieve, and the silicon-aluminum ratio of the zeolite molecular sieve is 5-10000:

1.

3. The iron-based molecular sieve catalyst according to claim 1 or 2, characterized in that: The molecular sieve is one or more of ZSM-5, CHA, FER, Beta and MOR.

4. The iron-based molecular sieve catalyst according to claim 1, characterized in that: The iron ion exchanger is one or more of ferric chloride, ferric nitrate, ferric sulfate, ferrous sulfate and ferric carbonate; the solvent is one or more of methanol, ethanol, ethylene glycol, water or glycerol.

5. A method for preparing the iron-based molecular sieve catalyst according to any one of claims 1 to 4, characterized in that: The following steps are involved: An iron ion exchanger and a solvent are prepared into an ion exchange solution, the ion exchange solution and a zeolite molecular sieve are subjected to ion exchange treatment to prepare a precursor, the precursor is washed with a solvent and dried, and then calcined after drying to prepare an iron-based molecular sieve catalyst.

6. The preparation method according to claim 5, characterized in that: The conditions of the ion exchange treatment include: temperature of 60-95°C, time of 20-120 min, and concentration of the ion exchange solution of 0.01-0.2 mol / L.

7. The preparation method according to claim 5, characterized in that: The calcination conditions include: temperature of 600-1000° C., and heat preservation for 2-4 hours.

8. The preparation method according to claim 5, characterized in that: The drying conditions include: temperature of 60-100° C. and time of 0.5-24 h.

9. Use of the iron-based molecular sieve catalyst according to any one of claims 1 to 4 in the dehydrogenation of light alkanes to light olefins, characterized in that: The following steps are involved: Light alkanes are subjected to a dehydrogenation reaction with a catalyst to produce light olefins, wherein the light alkanes include methane and ethane, and the light olefins include ethylene and propylene.

10. The use according to claim 9, characterized in that: The dehydrogenation reaction conditions include: inert atmosphere, temperature 550-700 °C, mass space velocity 0.2-5 h -1 .

Images